Travel trailers, which are towed vehicles usually having many of the conveniences of a home, are widely known and popular. One known type of travel trailer is commonly referred to as a “fifth-wheel” trailer, which is particularly adapted to be towed by a traditional pick-up truck. Namely, the forward portion of the fifth-wheel trailer is elevated above the bed of the pick-up truck and includes a mounting portion extending from the bottom of the elevated forward portion to a trailer mount, or hitch, secured to the bed of the pick-up truck.
Because of height restrictions imposed on travel trailers operating on most highways and aerodynamic considerations associated with towing a travel trailer at high speeds, the total desirable height above the ground for a fifth-wheel trailer is limited. Accordingly, the elevated forward portion typically has limited headroom, and therefore is usually used as a bedroom. The remaining aft portion of the fifth-wheel trailer typically includes a bathroom portion and general living portion.
Plumbing in trailer bathrooms typically includes gray and black water storage tanks and related tubing and valves extending from one or more toilets, shower drains, sink drains, and the like within the bathroom, to these storage tanks. To take full advantage of gravity, these types of storage tanks are typically mounted somewhere below the drains and toilet such that water from these devices flows freely through this tubing to its respective storage tanks. Accordingly, it is desirable to elevate the floor of the bathroom portion of a trailer above the bottom of the trailer.
Because of the limited headroom, it is not desirable to elevate the bathroom portion of the floor to the height of the forward bedroom floor of the trailer. Accordingly, the typical fifth-wheel trailer will usually longitudinally position the bathroom portion between the bedroom and living portion, and vertically elevate the floor of the bathroom portion to an intermediate height between the heights of the bedroom and living portion floors. The end result is a fifth-wheel trailer having three floor heights above the ground. A first height toward the aft of the trailer supporting the living portion, a second height toward the center of the trailer supporting the bathroom portion, and a third height toward the front of the trailer supporting a bedroom.
The area below the second height and the bottom of the trailer is typically enclosed and used as a storage space for the storage tanks, valves, and plumbing. In addition, this area is typically large enough to be used as a general storage area, or trunk space, for travel gear and the like. Accordingly, one or more access doors may be provided along the exterior walls of this storage area to provide access to this space. It is desirable for this storage area to be large and easily accessible.
The chassis of a typical fifth-wheel trailer must be sufficiently strong to support the trailer, and durable enough to resist weakening over a lifetime of prolonged use. Since the typical fifth-wheel trailer is regularly towed at high speeds and over rough or unimproved roads, the chassis must also withstand a tremendous amount of dynamic loads placed on it. Typical chassis materials are incredibly strong and durable. For example, a typical fifth-wheel chassis will be made of weldedtogether portions of elongate steel I-beam having an eight-inch to 12-inch vertical web. In general, the fewer parts and welds making up the primary load carrying chassis structure, the stronger and more durable the chassis.
A particularly strong chassis design is commonly known as a two level chassis. It's general design is shown and identified as prior art in FIG. 1A of U.S. Pat. No. 5,746,473 to Crean, the disclosure of which is hereby incorporated by reference. A two level chassis features an elongate horizontal lower beam (114, FIG. 1A of Crean), an elevated elongate horizontal upper beam (116, FIG. 1A of Crean), and an interconnecting vertical section (115, FIG. 1A of Crean) joined to both the lower and upper beams as shown in FIG. 1A of Crean, usually by welding. The elevated bathroom portion (122, FIG. 1A of Crean) of the typical two level chassis is typically a platform structure constructed of elongate wood members, metal members, or the like, and is supported above and by the lower beam (114, FIG. 1A of Crean). A storage space (140, FIG. 1A of Crean) is defined as the area below the elevated bathroom floor, but above the lower beam.
While the typical two level chassis is particular strong, the design also limits the amount of available storage in the storage area and access to that storage area. In particular, since the lower beam defines the lower portion of the storage area, the total volume of the storage area is narrowed by the vertical width of the webbing on that beam. For example, using typical chassis materials having an eight-inch to twelve-inch vertical web, the height of the storage area would be reduced by eight to twelve inches, thereby reducing the total volume of the storage area.
In practice, the height limitations imposed by positioning the chassis beam in this area prevents common oversized travel trailer-related items, such as traditional elongate, cylindrical 40 pound Liquid Petroleum Gas (“LPG”) tanks, from being accommodated easily in the storage area. In particular, in order for these types of items to fit within such known storage areas, they must either 1) be stored on their sides, thereby taking up much desirable floor space in the storage area, or 2) in some models be stored upright within a limited outrigger area between the chassis beam and storage area door, thereby blocking access to the majority of the storage area.
Some inventors have attempted to improve access to and the overall amount of storage space available in the storage area of a traditional fifth-wheel trailer. However, such improvements typically compromise chassis integrity and significantly increase chassis construction costs. For example, U.S. Pat. No. 5,746,473 to Crean teaches using a three-level chassis structure, which is also commonly referred to as a three-step chassis. FIG. 2A of Crean shows the general layout of such a three level chassis. Basically, the bottom level, or step, is a horizontal elongate lower chassis beam (202, FIG. 2A of Crean) that supports the aft living portion of the fifth wheel trailer. The forward bedroom is supported by a horizontal elongate upper chassis beam (210, FIG. 2A of Crean), and the bathroom portion is supported by a horizontal elongate intermediate chassis beam (208, FIG. 2A of Crean). The forward end of the lower chassis beam is joined to the back end of the intermediate chassis beam at an aft vertical section, and the forward end of the intermediate chassis beam is joined to the back end of the upper chassis beam at a forward vertical section. Accordingly, the chassis structure forms three steps from the lower chassis beam to the intermediate chassis beam and then the upper chassis beam.
As a result, the thick lower beam does not block the lower entrance to the storage area, thereby, Crean suggests, the storage area is more easily accessible. Crean also teaches mounting the black and gray water tanks to the intermediate chassis beam, thereby elevating them within the storage area. Accordingly, Crean reports that heavy objects need not be lifted as high to place them in the storage area.
While the three-level chassis in Crean offers these limited benefits, the design essentially doubles the number of parts and welds comprising the load carrying chassis components over a traditional two-level chassis. Accordingly, a three-level chassis is more costly to manufacturer and less durable than a similarly sized two-level chassis structure. Moreover, because the upper edge of the storage area is defined by the intermediate beam, and the thickness of the intermediate beam is essentially as thick as a traditional lower beam on a two-level chassis, the height of the storage area, and accordingly its volume, is still limited by the chassis structure. For example, where the intermediate beam is made of typical chassis materials having an eight-inch vertical web, the height of the storage area would be reduced by eight inches, thereby reducing the total volume of the storage area. Accordingly, as with a traditional top-level chassis, the height limitations imposed by positioning the intermediate chassis beam in this area still prevents common oversized travel trailer-related items, such as 40 pound LPG tanks, from being accommodated easily in the storage area. Moreover, positioning the black and gray storage tanks adjacent to the intermediate beams, as taught by Crean, further reduces the height of the storage area, thereby further compromising the storage area's ability to accommodate common large objects. Because the intermediate chassis beam is a primary load carrying chassis element, any reduction in the thickness of this beam around the storage area of a three-level chassis to increase the height of the storage area would compromise the strength of the chassis.
Accordingly, despite the known improvements to fifth-wheel travel trailer chassis designs, there remains a need for a chassis that has the strength, durability, and economy of a traditional two-level chassis, but also optimizes the height of the storage area beneath the bathroom portion to easily accommodate common large objects used with travel trailers. In addition to other benefits that will become apparent in the following disclosure, the present invention fulfills these needs.